Co-pending U.S. patent application Ser. No. 09/639,641 sets forth methods and devices for minimizig IBI in finite impulse response filters (xe2x80x9cFIRsxe2x80x9d), such as time domain equalizers (xe2x80x9cTEQsxe2x80x9d), which are commonly made a part of digital multi-tone transceivers (xe2x80x9cDMTsxe2x80x9d). These methods and devices take advantage of a newly discovered relationship between IBI and points along the xe2x80x9ctailsxe2x80x9d of a channel""s impulse response. More specifically, as disclosed in co-pending U.S. patent application Ser. No. 09/639,641, the present inventor discovered that each point along the tail of a channel""s impulse response contributes a non-uniform amount of IBI to a signal transmitted through the channel, rather than a uniform amount, as previously believed (both the signal and the channel""s impulse response will sometimes be referred to collectively as xe2x80x9cimpulse responsexe2x80x9d). Additionally, the present inventor discovered that the amount of IBI contributed by each point along the tail increases linearly. That is, taking as a reference point a time of reference (xe2x80x9cTORxe2x80x9d) of a channel""s impulse response (such as TORs disclosed in co-pending U.S. patent application Ser. No. 09/639,642), IBI increases linearly from point to point as the points are located farther and farther from the TOR (referred to hereafter as the xe2x80x9cnon-uniform contribution of IBIxe2x80x9d).
Co-pending U.S. patent application Ser. No. 09/639,641 sets forth novel methods and devices, such as TEQs for minimizing IBI based on these concepts. TEQs are commonly made a part of the front end of DMTs. One common example of a DMT is a digital subscriber loop (xe2x80x9cDSLxe2x80x9d) transceiver (collectively DMTs and DSL transceivers can be referred to as xe2x80x9ctransceiversxe2x80x9d). Besides needing to reduce IBI, it is important that FIRs or transceivers be affordable. Because cost is an issue, the circuitry (both hardware and software) making up an FIR, transceiver or the like must also be designed with cost in mind.
It might be very expensive to make the transceivers envisioned by co-pending U.S. patent application Ser. No. 09/639,641. Foreseeing this, the present inventor sought to discover new, simplified methods and devices for minimizing IBI in FIRs, transceivers and the like which were more economical.
Accordingly, it is a desire of the present invention to provide for methods and devices for simplifying the minimization of IBI in FIRs and/or transceivers.
It is another desire of the present invention to provide for methods and devices for simplifying the minimization of IBI in FIRs and/or transceivers by taking into consideration the non-uniform contribution of IBI.
Other desires will become apparent to those skilled in the art from the following description taken in conjunction with the accompanying drawings and claims.
In accordance with the present invention there are provided methods and devices for simplifying the minimization of interblock interference. Such methods and devices comprise applying a weighting function to an output signal, where the weighting function comprises correction factors based on a non-uniform contribution of interblock interference. Thereafter, incremental, differential coefficients are generated from a weighted output signal and sampled input signals. The incremental coefficients are used to generate an approximated set of differential coefficients which in turn are used to generate differential coefficients from a final set of approximated, differential coefficients.
The differential coefficients are then applied to a sampled input signal to substantially minimize interblock interference.
Devices for carrying out the features and functions of the present invention include TEQs, DMTs and DSL receivers.